Guard for collapsible underreamers



Sept. 20, 1932. CRUM 1,878,578

GUARD FOR COLLAPSIBLE UNDERREAMERS Original Filed Nov. 14, 1928 2Sheets-Sheet 1 BY WMMMW A TTORNEY INVENTOR.- Eo/and Z. Cram PatentedSept. 20, 1932 UNITED STATES PATENT OFFICE ROLAND R. CRUM, or wn r'rrnn,cALIronNIn, Assrenon, BY MESNE ASSIGNMENTS, 'ro J'QHN GRANT, or LOSANGELES, CALIFORNIA GUARD FOR COLLAPSIBLE UNDEBREAMERS Application filedNovember 14, 1928, Serial No. 319,277. Renewed December 3, 1931.

This invention relates to collapsible underreamers and more especiallyto means for protecting the cutters from damage while in collapsedposition and during passage through the well casing string.

Underreamers of the collapsible type having laterally projectablecutters are in many instances so disposed on the underreamer body as toride along thewell casing while being lowered. The well casing string isthus subject to damage by cutting, but the cutters themselves aresubject to greater damage due to wear and abrasion as a result of thefrictional dragging contact with the well casing string. This causesdulling of the edges of the cutters making them less eflicient. r

The present invention contemplates means to guard and hold the cuttersfrom contact with the casing string. It is the primary object of thisinvention to provide such means so mounted that upon rotation of thetool they will be displaced enabling the cutters to fully expand andperform their cutting function without interference.

These objects together with other objects and-correspondingaccomplishments are obtained by means of the embodiments of my inventionillustrated in the accompanying drawing, in which s Fig. 1 is anelevation of a complete underreamer with guards detached, the cuttersbeingin expanded posit-ion; Fig. 2 is an axialsection through theunderreamer within acasing, the underreamer being in collapsed positionand the guards mounted thereon; Fig. 3 is an axial seotionsnowing thecutters below a casing and in expanded position, the guards having beendisplaced; Fig. 4 is a sectionas seen on the line 1- 1 of Fig. 2; Fig. 5is a section as seen on the line 5-5 of Fig. 1, on an enlarged scale,the cutter spindle being shown in elevation and with a guard mountedthereon; and Fig. 6 is a perspective view of a guard.

Referring more particularly to the drawings, a body 7 has an upper pinadapting it' for connection to a drill string and at the bottom has adetachable box 8 to receive 50 the pin of a drilling tool or anyotherSuitable device. Extending through the body is a circulation passage 9.Cutter accommo'dating cavities 10 are provided in the periphery of thebody. These cavities have disposed therein cutterswhich'are projectableinto expanded position and retractable into collapsed position. At the"upper ends of the cavities are pockets 11 to receive the upper ends ofcutter spindles. Formed on thebody'and adjacent the pockets are inclinedguide surfaces 12- for directing the spindles into the pockets. At thelower ends of the cavities are inclined bearing surfaces 13 for thespindles to bearagainst. Suitable vent holes are provided for thepockets to prevent trapping of circulation fluid therein, and coursesconnect with the circulation passage 9 to deliver wash water to thecutters and cavities.

There are four cavities shown herein, but there may be more or less, andin each cavity is mounted a cutter spindle 14. The cutter spindles areangled having knees 15 dividing each'spindle'into two. journal sectionsfor roller cutters. The lower ends of the spindles have bearing surfaces16 for engagement with the corresponding bearing surfaces 13 on thebody. These spindles are of such length that they may be movedlongitudinally and bear at their lower ends against the surfaces 13. Inthe upper positions of the spindles, the lower ends are moved a slightdistance outwardly. The upper ends of the spindles are in the, form offingers 17 which will snugly fit into the pockets 11. The ends of thefingers are inclined in a direction corresponding tothe guide surfaces12 as indicated by 18. In collapsed position as shown in Fig. 2, thefingers are out of the pockets and their ends are engaged with the guidesurfaces. In expanded position, the fingers, as shown in Fig. 3 aredisposed in the pockets. Mounted upon the journal sections are rotativecutters 19 suitably held in position by end collars.

The box member 8 is secured to the lower end of the body and provides ashoulder upon which a compression spring 20 is mounted. Slidably mountedover the box is a follower 21 of sleeve form arranged to have thecompression spring bear against Recesses 22 are formed by upstandingabutments on the follower so as to form seats or pockets for the lowerends of the spindles 14:. The follower and spring tends to move thespindles upwardly and outwardly.

The underreamer maybe collapsed by forcing the cutter mechanismdownwardly so that the fingers 17 are out of their pockets and theinclined bases of the spindles rest against the guide surfaces 13 asshown in this position they are positively held against lateral movementwith respect to the drilling axis of the underreamer.

It will be noted that without guards the cutters would ride againstthecasing when disposed therein. This results in the cutting edges of therollers being dulled while being lowered with resultant decrease ofefficiency. To overcome this, I have provided each knee 15 with a groove23.. The upper and lower walls of the grooves are preferably parallel,and the outer faces of the knees are flat. A guard is provided for eachknee comprising a wear portion 24 to cover the knee and hav ing a tongue25 corresponding to the groove 23. The wear portion is of such thicknessthat when the guard is disposed in place upon its knee, the guard willextend laterally beyond the cutters and thereby hold them from contactwith the wall of the casing. However, the ends of the grooves are openso that upon rotation of the tool, the guards will be enabled to movecircumferentially in relation to the underreamer and be displaced,dropping to the bottom of the hole. Displacement is caused by expansionof-the cutters and engagement of the guard with the side of the hole. I

While a specific type of collapsible underreamer has been describedherein, it will be understood that the invention is not limited to usewith such species of underreamer. The specific type of underreamer hasbeen described for illustrative purposes only.

The invention is adapted to be embodied in other species of underreamersand in its broad aspect is not limited to underreamers having rollercutters. The scopeof'the invention is apparent from the appended claims.l

What I claim is 2-.- I

1. The combination with a collapsible underreamer having a body andlaterally projectable cutters, of guards projecting from the underreamerlaterally beyond the cutters, said guards being mounted on'saidunderreamer. to be displaceable by rotational movement of saidunderreamer.

2. The combination with a collapsible underreamer having a body andlaterallyprojectable cutters of guards mounted on i said cutters bytongue and groove connections open at the ends so that said guards maybe displaced by rotational movement of said underreamer, said guardsextending laterally beyond said cutters.

5. The combination with a collapsible underreamer having roller cuttersmounted on spindles projectable laterally of said body, of guardsmounted on said spindles and extending laterally beyond the cutters,said guards being mounted on said spindles to be displaceable byrotational movement of said underreamer. v

6. The combination with. a collapsible underreamer having roller cuttersmounted on spindles projectable laterally of the body,

of guards mounted on said spindles by tongue and groove connectionsopenat the ends so as to be displaceable, saidguards extending laterallybeyond said cutters.

7. The combination with a collapsible underreamer having cuttersprojectable laterally' of said body comprising angled spindles extendinglongitudinally of said a body, roller cutters journalled on saidspindles, and guards mounted on the knees of said spindles so as to bedisplaceable by rotational fmovement of said underreamer.

8. The combination with a collapsible underreamer having abody withroller cutters projectable laterally of'jthe body comprising angledspindles extending longitudinally of the body, rollercuttersi'journalled thereon, and guards mounted on the lmees of saidspindles by tongue and grooveconnections open at the ends so as to bedisplaceable, said guards extending laterally beyond said cutters. l

9. The combination with a collapsible underreamer having a body andlaterally projectable cutters, of guards projecting from the underreamerlaterally beyond the cutters, said guards being mounted on theunderreamer to be displaoeable by frictional engagement with the side ofthe hole. 1 10. The combination with a collapsible underreamer having abody and laterally projectable cutters, of guards mounted on the wcutters and projecting outwardly laterally therefrom, said guards beingmounted on the cutters to be displaceable with reference thereto byfrictional engagement with the side of the hole.

In Witness that I claim the foregoing I have hereunto subscribed my namethis 3rd day of November, 1928.

ROLAND R. CRUM.

